990 resultados para Compound Poisson Process


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The young child's ability to go through a genuine mourning process has been a source of controversy in the psychoanalytical literature. This may seem surprising, considering that mourning is essential for and inherent to psychic development. This paper attempts to show that the young child's ability to go through a mourning process does not depend mainly on ego maturity, nor just on an acknowledgment of a loss in the external world, nor on the child's understanding the idea of death at an intellectual and cognitive level. But it may depend mainly on the establishment of the primordial mourning process inherent to the separation of the transnarcissistic mother-child relation and on the existence of the objectalizing function (A. Green, 1986) in the remaining or substitute parent's psyche. A clinical example serves to illustrate these hypotheses.

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In a recent paper Bermúdez [2009] used bivariate Poisson regression models for ratemaking in car insurance, and included zero-inflated models to account for the excess of zeros and the overdispersion in the data set. In the present paper, we revisit this model in order to consider alternatives. We propose a 2-finite mixture of bivariate Poisson regression models to demonstrate that the overdispersion in the data requires more structure if it is to be taken into account, and that a simple zero-inflated bivariate Poisson model does not suffice. At the same time, we show that a finite mixture of bivariate Poisson regression models embraces zero-inflated bivariate Poisson regression models as a special case. Additionally, we describe a model in which the mixing proportions are dependent on covariates when modelling the way in which each individual belongs to a separate cluster. Finally, an EM algorithm is provided in order to ensure the models’ ease-of-fit. These models are applied to the same automobile insurance claims data set as used in Bermúdez [2009] and it is shown that the modelling of the data set can be improved considerably.

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A collection of spherical obstacles in the unit ball in Euclidean space is said to be avoidable for Brownian motion if there is a positive probability that Brownian motion diffusing from some point in the ball will avoid all the obstacles and reach the boundary of the ball. The centres of the spherical obstacles are generated according to a Poisson point process while the radius of an obstacle is a deterministic function. If avoidable configurations are generated with positive probability Lundh calls this percolation diffusion. An integral condition for percolation diffusion is derived in terms of the intensity of the point process and the function that determines the radii of the obstacles.

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A new hypothesis is formulated to explain the development of rapakivi texture in and around the mafic enclaves of porphyritic granitoids, i.e. in environments involving magma mixing and mingling. The formation of a plagioclase mantle around alkali feldspar megacrysts is attributed to the localized presence of a melt resulting from the reaction of these megacrysts, with host hybrid magma with which they are in disequilibrium. This feldspathic melt adheres to the resorbed crystals and is virtually immiscible with the surrounding magma. Its composition is modified in terms of the relative proportions of K2O, Na2O, and CaO through selective diffusion of these elements, thus allowing the specific crystallization of andesine. With decreasing temperature, the K-feldspar, again stable, crystallizes along with the plagioclase, leading to mixed mantle structures.

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The Institute of Public Health in Ireland is an all-island body which aims to improve health in Ireland by working to combat health inequalities and influence public policies in favour of health. The Institute promotes co-operation in research, training, information and policy in order to contribute to policies which tackle inequalities in health. Over the past six years the Institute has worked closely with the Department of Health and Children and the Department of Health, Social Services and Public Safety in Northern Ireland to build capacity for Health Impact Assessment. The Institute takes the view that health is determined by policies, plans and programmes in many sectors outside the health sector as well as being dependent on access to and availability of first class health services. The importance of other sectors is encapsulated in a social determinants of health perspective which recognises that health is largely shaped and influenced by the physical, social, economic and cultural environments in which people live, work and play. Figure 1 illustrates these multi-dimensional impacts on health and also serves to highlight the clear and inextricable links between health and sustainable development. Factors that impact on long-term sustainability will thus also impact on health.

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La contaminación de suelos y aguas subterráneas es uno de los problemas ambientales más extendidos en gran parte de los terrenos industriales de Cataluña. En este proyecto se ha analizado el proceso de gestión de la contaminación: caracterización, remediación y seguimiento de la descontaminación en suelos y aguas subterráneas por un caso de afección por organoclorados (percloroetileno) y otros contaminantes (hidrocarburos, selenio y cromo) en un emplazamiento industrial situado en una zona agroforestal (superficie de 81.462 m2). A partir de la implantación en la empresa del sistema de gestión ISO 14.001 en 1.996, se abrieron diferentes proyectos de gestión para los posibles contaminantes. Por las mismas fechas, también se detectó una afección por selenio en aguas subterráneas, ajena a la empresa de estudio. Por el momento, el único contaminante que ha requerido de un proceso de descontaminación ha sido el percloroetileno. En suelos se emplea el método “soil vapor extraction” y en aguas subterráneas el método “airstripping”. Finalmente, se ha llevado a cabo una comparación de los costes reales derivados del proceso de descontaminación del percloroetileno en contra de los costes que se hubiesen derivado la implantación de medidas de prevención de la contaminación. El resultado de la valoración indica que la descontaminación de éste compuesto requiere de una inversión económica importante, unas 10 veces más elevada que los costes derivados de las medidas de prevención.

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A collection of spherical obstacles in the unit ball in Euclidean space is said to be avoidable for Brownian motion if there is a positive probability that Brownian motion diffusing from some point in the ball will avoid all the obstacles and reach the boundary of the ball. The centres of the spherical obstacles are generated according to a Poisson point process while the radius of an obstacle is a deterministic function. If avoidable con gurations are generated with positive probability Lundh calls this percolation di usion. An integral condition for percolation di ffusion is derived in terms of the intensity of the point process and the function that determines the radii of the obstacles.

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Estudi realitzat a partir d’una estada a la Universidad de Zaragoza, Espanya, entre novembre del 2007 i abril del 2008. Mycobacterium vaccae és un micobacteri ambiental de creixement ràpid molt estudiat pel seu interès com a possible ús immunoterapéutic en el tractament de la tuberculosis i altres malalties. M.vaccae a l’igual que altres micobacteris presenta dues morfologies colonials: llisa i rugosa. M.vaccae ATCC15483T té originàriament una morfologia llisa. Quant aquest es cultiva en medi sòlid a 30ºC apareixen espontàniament variants rugoses estables que no reverteixen a llises. El motiu pel qual aquest procés té lloc no es coneix, encara que s’ha descrit en Mycobacterium smegmatis i en Mycobacterium avium que els lípids de la paret cel•lular es troben involucrats en aquest canvi de morfologia colonial. L’anàlisi dels contingut en lípids i glicolípids de la paret cel•lular de les dos variants morfològiques de M.vaccae, ens ha indicat que les soques llises presenten un compost extracel•lular que no es troba en les rugoses i que mitjançant l’anàlisi estructural d’aquest compost ha sigut identificat com un polièster extracel•lular de cadena llarga. El present estudi s’ha centrat en determinar els gens implicats en la síntesis d’aquest compost. Per a realitzar aquest anàlisi genètic s’ha construit una llibreria de mutants per transposició de la soca llisa de M. vaccae mitjançant un plàsmid ts/sac i un transposó. S’han obtingut colònies de morfologia rugosa on el plàsmid s’ha insertat en la zona del genoma que codifica per aquest compost extracel•lular. Aquests nous mutants s’han analitzat mitjançant tècniques moleculars (PCR, Southern y seqüenciació). A mès, s’ha construit una llibreria genòmica amb DNA de la soca llisa en plàsmids replicatius de micobacteris derivats de pAL5000 i s’ha transformat la soca rugosa seleccionant per a un fenotip llis estudiant els gens que complementen.

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The presence of Triatoma rubrovaria in Brazil has only been confirmed in the States of Paraná and Rio Grande do Sul (RS), where it is found naturally infected with Trypanosoma cruzi. In the wild environment it occurs in rocky habitats and has an eclectic diet, feeding from cockroaches, reptiles and mammals. Data from the Chagas Disease Control Program obtained by the Fundação Nacional de Saúde, between 1975 and 1997, indicate a growing domiciliary and peridomiciliary invasion of T. rubrovaria in RS, where it has become the most frequently Triatominae species captured in this state since the control of Triatoma infestans. In order to monitor this process, we analyzed collection data derived from 22 years of control campaigns against T. infestans. Collection data for triatomines from domestic habitats show an inverse relationship, with high numbers of T. infestans and low numbers of T. rubrovaria during 1976-1987, compared to the following ten years, 1986-1997, when the number of T. infestans dropped drastically and that of T. rubrovaria increased. There are no consistent indications of intradomiciliary colonization by T. rubrovaria, since only low numbers of nymphs have been captured in the intradomiciliary ecotopes. Nevertheless, this species appears to have preadaptive characteristics for anthropic ecotopes, and should be kept under constant epidemiological surveillance.

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The aim of this paper is to analyse the effects of human capital, advanced manufacturing technologies (AMT), and new work organizational practices on firm productivity, while taking into account the synergies existing between them. This study expands current knowledge in this area in two ways. First, in contrast with previous works, we focus on AMT and not ICT (information and communication technologies). Second, we use a unique employer-employee data set for small firms in a particular area of southern Europe (Catalonia, Spain). Using a small firm data set, allows us to analyse the particular case of small and medium enterprises, since we cannot assume they have the same characteristics as large firms. The results provide evidence in favor of the complementarity hypothesis between human capital, advanced manufacturing technologies, and new work organization practices, although we show that the complementarity effects depend on what type of work organization practices are used by a firm. For small and medium Catalan firms, the only set of work organization practices that improve the benefits of human capital and technology investment are those practices which are more quality oriented, such as quality circles, problem-solving groups or total quality management.